Grinding machine



Filed May 15, 1967 5 Sheets-Sheet l n m h INVENTOR ARTHUR W. Mc ELROY ATTORNEY A. w. M ELROY GRINDING MACHINE Jan. 6, 1970 Filed May 15, 1967 5 Sheets-Sheet 2 ATTORNEY Jan. 6, 1970 A. w. M ELROY GRINDING MACHINE 5 Sheets-Sheet 3 Filed May 15, 1967 FIGS INVENTOR ARTHUR W- Mc ELROY ATTORNEY Jan. 6, 19.70

AL MGELRQY 3,487,583

GRINDING MACHINE Filed May 15, 1967 5 SheetsSheet 5 INVENTOR ARTHUR w. McELROY ATTORNEY United States Patent 3,487,583 GRINDING MACHINE Arthur W. McElroy, Wellsville, Ohio, assignorto Ferro Corporation, Cleveland, Ohio, a corporation of Ohio Continuation-impart of application Sen No. 425,005,

Jan. 12, 1965. This application May 15, 1967, Ser.

N0. 642,636 Int. Cl. B24b 7/14 U.S. Cl. 51-34 ABSTRACT OF THE DISCLOSURE Automatically cyclical device for grinding a multiplicity of substantially parallel surfaces, said device consisting of a plurality of spaced grinding means reciprocally movable in one plane, clamping means, for holding surfaces to be ground, movable in-a plane intersecting said first plane; one or the other of either said grinding means, or means for carrying an item to be ground, manually reciprocated to one extremity of its movement against the force of springs, said single manual movement, combined with a single reciprocating means, causing the grinding means to make a first pass over one set of surfaces to be ground, thereby automatically indexing the grinding means with respect to a second set of surfaces to be ground, following said first pass, and, still automatically, causing said grinding means to make a second pass over a different set of surfaces to be ground, and returning the apparatus to its starting point. p

This application is a continuation-in-part of my copending application Ser. No. 425,005 filed Jan. 12, 1965-, since abandoned, upon filling the instant application.

This invention relates to new and useful improvements in ceramic tile grinding machines. More particularly, the invention relates to grinding machines which automatically grind or hone the shelves of a compact tile setter.

It has always been a problem in the, ceramic tile industry to prevent warpage of flat tile bodies during the firing operation thereof. To offset this warpage difficulty, it has been a general practice to design setters in which each tile is fully supported over its entire surface by a replaceable or fixed fiat refractory slab. This method has proved to be unsatisfactory since it lowers the fue-l,ef--

ficiency by introducing excessive.amountsof dead mass into the firing operatiomFurtherrnore, the warpage problem was not entirely eliminated dueto the warpage of the supporting slab for each individualtile during the firing, thereby inducing a corresponding warpagelin a .tile supported thereon. I I v I Recently it has been shown, in the;.-Uni ted States patent application Ser. No. 166,757,. filedfJan. 17, 1962,.now US. Patent 3,169,295, that warpage of fiatfltile bodies during the firing operation can besubstantially minimized by specially designed setters on, which each tile is supported at its respective edges by two opposed and complementary tile shelves having a precision relationship. However, the aforesaid tilev shelves'withinthe setter, must be machined to extraordinary fine; tolerances, with respect to a theoretical reference place encompassing the,

machined tile supporting surfaces of the tworshelves, in

order to provide substantially parallel supporting points 6 "Claims It is a further object of this invention to provide a machine especially adapted for honing the opposed shelves of a compact tile setter having two or more cells in a manner such that the tiles positioned thereon during the firing operation will lie in a substantial plane.

In the accompanying drawings:

FIG. 1 is a top plan view of the grinding apparatus in accordance with this invention;

FIG. 2 is a side view of the grinding apparatus having a portion thereof cut away;

FIG. 3 is a side elevation view of the tile setter specifically adapted to have its shelves ground by the apparatus of this invention;

FIG. 4 is an enlarged side elevation view of two opposed shelves as shown in FIG. 3; and

FIG. 5 is an enlarged perspective view of the cam plate of FIG. 2.

FIG. 6 is a side view of a variation of the apparatus depicted in FIG. 2.

This invention obviously can be employed to grind various types of ceramic tile setters, particularly those having a multiple number of cells. However, for illustrative purposes, the description throughout the specification is directed to an apparatus designed to grind the shelves of tile setters having two cells.

In general, the novel grinding apparatus of the present invention comprises in combination:

a support;

grinding means vertically movably mounted on said sup port;

a table movably mounted on said support, said table adapted for longitudinal movement;

means mounted on said table for fastening an object to be ground thereto;

means mounted on said support operatively connected to said table and adapted to move the same in a longi tudinal direction through said grinding means, thus grinding a desired portion thereof from said object fastened to said table;

means mounted on said support for moving said table in a reverse longitudinal direction after said table with its object to be ground fastened thereto has passed through said grinding means; and means for moving said grinding means to a different vertical position, thus enabling a different portion of the object fastened to said table to be ground as it passes through the grinding means during its reversed longitudinal movement.

The preferred means for moving said grinding means to a different position comprises a lever pivotally mounted on said support, said lever having the said grinding means operatively connected thereto; a cam mounted on the bottom surface of said table, and a cam roller mounted on said lever adapted to follow said cam as the said table moves in a longitudinal direction thus in so doing etfec grinding stones positioned thereon, said spindles operatively connected to said electric motor by a belt and pulley arrangement.

The preferred means mounted on said table for fastening an object thereto comprises at least three parallel forks extending from two common upright arms mounted in a parallel relationship at the rear of said table, said forks adapted to lift the ceramic articles to be ground in a slightly elevated position above the said table, and two adjustable clamp units mounted on each side of said table in parallel relationship and adapted to hold the said article to be ground firmly against said forks in its slightly elevated position.

Before undertaking a detailed explanation of the specific apparatus depicted in FIGURES 1 and 2, it may be helpful to understand in a general manner the operations of the apparatus as previously described. In this regard, it may be of help to take FIGURE out of order, since almost all of the operations of the apparatus entail some operative connection with the cam means 22 of FIGURE 2 which is more clearly shown in the enlarged perspective view of FIGURE 5.

A cam roller means 90 operatively connected to a vertically mounted grinding means is adapted to travel around cam 22 in the direction shown by the drawing. For the sake of clarity in explaining the operation of the cam and the cam roller means 90, cam roller means 90 is additionally shown by dotted lines in four different positions marked position A, position B, position C, and position D, through which the cam roller moves during its travel around cam 22.

The vertically tmovable grinding means is maintained under a positive upward spring tension at all times against an upper indexing limit, such as, for example, a plurality of stop bolts. The grinding means is operatively attached to cam roller 90 which at the start of any given cycle is in position A as shown in FIGURE 5. By forcing the entire grinding means assemblyincluding the cam roller downward past one-way latch 86A, and into position B of FIG- URE 5, the grinding assembly remains under strong positive upward spring tension but is held from any upward movement by the one way latch. When the cam roller 90 moves into position B of FIGURE 5, it activates a horizontal movement in a first direction of the movably mounted table means and cam 22 (which is operatively connected to the movably mounted table) from a first indexed osition to a second indexed position during which movement the grinding means is maintained by cam roller 90 in a lowered vertical position. When cam means 22 has traveled into the second indexed position cam roller 90 will be in position C of FIGURE 5, and the positive upward spring tension under which the grinding assembly is being maintained will pull the grinding assembly into the first or upper position, pulling the cam roller 90 by one-way lat-ch 863, into position D of FIG- URE 5. Arrival of the calm roller 90 at position D of FIGURE 5 then activates a reverse movement of the table and {cam means 22 in a reverse direction until the table and cam 22 have returned to their first indexed position at which point cam roller 90 will have returned to position A of FIGURE 5 Additionally, it will be obvious that the arrival of the cam roller means in position A can either turn the machine off to allow for a placement of a new object to be ground, e.g., a tile setter such as that previously noted, or could trip a limit switch which would activate some means to force a downward movement of the grinding assembly to place the cam roller means in position B, this last alternative being one which would be employed only in the event of continuous operations wherein it was possible: to very quickly replace the grounded tile setter with an unground tile setter for the new cycle.

It will now be seen that if a compact tile setter having a plurality of tiers of shelves, such as that illustrated by FIGURE 3, is suitably clamped to the movably mounted table, when calm roller 90 is forced from position A of FIGURE 5 to position B of FIGURE 5 the entire grinding assembly will be maintained in a lower indexed position and the movably mounted table means and the tile setter mounted thereon will move horizontally. The plurality of grinding stones which have been placed and maintained in a predetermined space apart relationship will be brought into contact with the tops of the shelves grinding olf any high spots as depicted in FIGURE 4, the horizontal movement of the movably mounted table con i uing until all or the g ndings o s have P s ed all the way through the tile setter. At this point cam roller will have reached position C of FIGURE 5 and the spring tension on the grinding assembly will pull it upwards into its first indexed position and the horizontal movement of the movably mounted table will be reversed.

It should now be obvious that the grinding stones will again pass through the tile setter, and in the preferred embodiment the number of grinding stones which will affect any one cell is equal to at least half the number of tiers of shelves so that at least one half of the shelves will be ground in the travel of the movably mounted table in the first direction and the other half will be ground when the movably mounted table returns to its original position.

From the foregoing it should also be clear that the length of the cam 22 is directly proportional to the length of travel of the movably mounted table and that the height of the cam 22 is a direct function of the vertical distance between abutting shelves. It should be equally obvious that these proportional relationships need not be the same, that is 'to say, by well known appropriate mechanical linkages it is possible to have a cam whose length is one half the distance to be traveled by the movably mounted table while the height of the cam could be one third, or one quarter, or less, or four, or five times the distance between any two abutting shelves or any four abutting shelves.

The grinding wheels could be so spaced as to grind every other shelf space when in the downward position while the table is traveling to its first indexed position; thgl if the distance of travel of the vertically mounted grinding means is equal to the vertical distance between two abutting shelves, the return of the grinding means to its first indexed position would place the grinding means in a position to grind the unground shelves when the table reverses its direction of travel and returns to its first indexed position. Likewise, it is possible to have, for example, 12 shelves to be ground and to have six grinding wheels per cell, the vertical distance between the center of each of the abutting shelves being the distance between any two abutting shelves, and at the end of the forward grinding cycle, the entire grinding assembly would rise a distance equal to the distance between six shelves or six times the distance between any two shelves and grind the sixppper shelves on the return grinding cycle.

Referring to the drawings, table 2 is mounted on a supporting frame 30 so as to provide a longitudinal movement on said frame along the parallel rods indicated as 28 which serve as guideways for the aforesaid table 2. In order to prevent undue breakage, table 2 has positioned thereover a rubber pad 5. Mounted at the rear and to the side of table 2 and parallel to one another are two upright; arms 7a and 7b best shown in FIGURE 1. The arms 7a, and 7b have positioned thereon in parallel relationship three forks 6, two forks on arm 7a and one on arm 7b, which are designed to lift the object to be ground, namely the setters indicated as 3 free of table 2 and at I the. same time line up the shelves 4 of the aforesaid setter 3't o the grinding stones 16 rotatably mounted on the spindles 14. The setter 3 shown individually in FIGURES 3 and; 4 and as mounted on the apparatus of this invention'in FIGURES 1 and 2 are held in a slightly elevated position free of the table 2 by the shelves 4 resting on the three forks 6 and held in place by the adjustable clamp units 8. When setter 3 is mounted in place it rests on rubber pad 5 rather than directly on table 2. In this way the bottom surface of setter 3 is indirectly supported by table 2, through rubber pad 5 which prevents undue vibration breakage of the setter 3. A ca-m plate 22 described in more detail below is attached to the bottom of said table 2 and extends vertically downward therefrom. Connected to the front portion of the cam plate 22 is a rod 24 which extends into an air cylinder 26. The said cylinder 26 is mounted on frame 30 and upon actuation will draw the d 2 n e na y nd cau e t b e 2 to be moved in a longitudinal direction along the rod guideways indicated as 28. Attached to the upper surface sides of table 2 and to the frame 30 are hydro-check units 31a and 31b which are adapted to provide a smooth and even table movement. The hydro-check units 31a and 31b controlled by the adjustments 32a and 32b.

A lever is pivotally monuted at one end 33 underneath the frame to the fulcrum 34. It will be noted that the fulcrum 34 is actually the lower end of the fulcrum bar 35 which is adjustable in an up or down manner by the fulcrum bar adjusting nuts 37a and 37b. The indexing box 12 is movably connected to one end of the linkage bar 36 which in turn is movably connected at its other end to the adjustable indexing bar linkage clamp 38 mounted on the lever 10 near the fulcrum 34, said fulcrum being an extension of the frame 30. The indexing box 12 is mounted in such a manner as to provide vertical movement along the vertical rod guideways 40a, 40b, and 400 and 40d whenever lever 10 is moved up or down by pivoting the same at fulcrum 34. The threaded rods 42a and 42b are mounted on each side of the frame 30 laterally and to the front of the indexing box 12. A third threaded rod 420 is mounted on the frame 30 at the rear thereof and near the middle of said indexing box 12. All three threaded rods 42a, 42b and 420 are mounted so as to extend through extensions of the indexing box 12. Positioned on each of the three threaded rods 42a 42b and 420 are the indexing box stops 44a and 44b. They control the distance of vertical movement of said indexing box 12. Since the fulcrum bar 35 is adjustable in an up or down manner, the lever 10 is similarly adjustable and permits the indexing box 12 to be forced against the indexing box stops 44a and 44b under an equal pressure thus arranging the indexing box 12 in a solid immovable position.

The indexing box 12 comprises two side plates 46a, 46b and front and rear cross plates 48a and 48b respectively. It will be noted that the front cross plate 48a extends laterally beyond both of the side late 46a and 46b. The threaded rods 42a and 42b are mounted one on each side of the indexing box 12, and on the frame 30 in such a manner as to extend through the said lateral extensions of the front cross plate 48a. Similarly the third threaded rod 420 also mounted on the frame 30 extends through the rear extension of the rear cross plate 48b. The purpose of the three threaded rods 42a, 42b and 420 is to provide an adjustable mount for the indexing box stops 44a and 44b. It is clear that various adjustments of the indexing box stops are possible thereby controlling any vertical movement of the said indexing box 12. Positioned laterally to each of the vertical rod guideways 40a, 40b, 40c and 40d are the coil springs 50a, 50b, 50c and 50d. They are mounted between a lateral extension at the front and rear of the indexing box side plates 46a and 46b respectively and the frame 30. Thus as indexing box 12 moves in a downward movement, the springs 50a, 50b, 50c and 50d are compressed giving a desired balance to the said indexing box 12.

An electric motor 52 is attached to the indexing box 12 by utilizing the mounts 54, 56, 58 and 60. Switch 62 mounted on the front of frame 30 when actuated is adapted to start motor 52 through an electrical system which forms no part of this invention and is consequently not shown in the drawings. A pair of spindles14a and 14b having the grinding stones 16 mounted thereon are attached in a parallel manner to the front cross plate 48a of indexing box 12 through the spindle arm 56 and the spindle yoke 57. It should be noted that any variation of the number of spindles or manner of their attachment to the indexing box 12 is within the scope of this invention, said variation being dependent upon the type of ceramic article to be ground. Similarly, although the preferred embodiment of this invention utilizes two parallel spindles The motor 52 rotates the spindles 14a and 14b and the grinding stones 16 mounted thereon through a belt and pulley system involving belts 64 and 68, pulleys 70 and 72 and belts 74 and 76. The pulleys 70 and 72 are rotatably mounted on the pulley mounts 78a and 78b, which are fixed to the rear projection of the indexing box front cross plate 48a. Belts 64 and 68 are adjusted by tightening or loosening the back-up bolts 80a and 80b and draw bolts 82 positioned on the rear of the rear cross plate 48b. This adjustment will slightly change the position of the pulleys 70 and 72 thereby either tightening or loosening the aforesaid belts 64 and 68.

The cam plate 22, shown in place in FIGURE 2, and shown in perspective in FIGURE 5, is mounted on the bottom of table 2. This can be accomplished either by a direct connection of the cam plate 22 to the bottom surface of table 2, or by mounting extensions 23 and 25 to the bottom surface of table 2 and then connecting the opposite end of said table rods 23 and 25 to the cam plate 22. Mounted on both the front and rear of said cam plate 22 are a pair of limit switches 84a and 84b in close proximity to the front and rear of the cam surface machine on cam plate 22. Also at the front and rear of the aforesaid cam plate 22, one-way latches 86a and 86b are movably mounted. They are both maintained under a constant spring pressure by the springs 88a and 88b, said springs each having one end connected to the respective one-way latches 86a and 86b and the other end thereof connected to the cam plate 22. A cam roller 90 is positioned on lever 10 in such a manner that upon moving lever 10 to a downward position, the cam roller 90 moves past the one-way latch 86a mounted at the back of cam plate 22 and at the same time trips the limit switch 84a. This actuates the air cylinder 26 through an electrical circuit not shown which pulls the rod 24 therein and thus also pulls table 2 in a longitudinal movement toward the rear of the apparatus. As table 2 moves rearward, the stationary cam roller 90 mounted on lever 10 follows the moving cam surface on the cam plate 22. It will be noted that the front cam surface on cam plate 22 is similar to the back surface inasmuch as it curves abruptly upwards; and as this portion of the cam surface reaches the cam roller 90 the pressure on said cam roller is relieved and it also moves upwards past the one-way latch 86b automatically and contacts the limit switch 84b which reverse the action of air cylinder 26 through an electrical circuit now shown. This causes rod 24 to be forced out of said cylinder 26 and thereby moves table 2 in the opposite direction until the air cylinder 26 has forced table 2 as far to the front of the apparatus as cylinder 26 is adapted or designed to move. The cam roller 90 maintains a position on the upper cam surface of cam plate 22 during the forward movement of table 2 and is so positioned at the end of the reversed air cylinder 26 movement that a downward directed movement of the lever 10 on which cam roller 90 is mounted will again start the identical action in the manner as has been previously described.

The indexing box 12 as stated above, is connected to lever 10 through the indexing linkage bar 36 and the indexing box linkage clamp 38. Thus when the lever 10 is moved to its lowest position, the indexing box 12 is also moved vertically downwards along the vertical guideways 40a, 40b, 40c and 40d and is forced to a position resting on the stops 44b mounted on the threaded rods 42a, 42b and 420. It is stressed that clamp 38 and the fulcrum 34 are adjusted to enable the indexing box 12 to maintain a solid position when considerable pressure is exerted against the stops 44a and 44b. The grinding stones 16 mounted on the front of the indexing box 12 are i so positioned when the indexing box 12 is forced against stops 44b they will grind half of the number of opposed setter shelves 4 as table 2 on which the tile setters 3 are positioned moves toward the rear of the apparatus. The lever 10 and cam roller 90 mounted thereon both move upwards at the end of the rearward movement of table 2. This is due to the cam roller 90 reaching the end of the lower cam surface on cam plate 22. Since lever 10 is under a considerable pressure during the time the cam roller 90 mounted thereon moves on the lower cam surface, the sudden release of that pressure forces the lever 10 and the cam roller 90 mounted thereon in an upward direction over the one-way latch 86b tripping limit switch 84b and at the same time positioning the cam roller 90 on the top cam surface of the cam plate 22. When lever 10 moves upwards as described above, the indexing box 12 operatively attached thereto near the fulcrum 34 of said lever 10 also moves upwards along the guideways 40a, 40b, 40c and 40d and becomes positioned under considerable pressure against the stops 44a mounted on each of the threaded rods 42a, 42b and 420. The very high pressure at which the indexing box 12 is maintained against stops 44a and 44b prevents substan tially any movement of said indexing box, and thus also prevents any movement of spindles 14 and grinding stones 16 both mounted on the front portion thereof. The position at which spindles 14 and grinding stones 16 are maintained after the indexing box 12 on which they are mounted has moved to its upper position is such that the remaining half of the number of opposed setter shelves 4 are ground as table 2 moves toward the front of the frame 30.

Thus, in operating the machine, motor 52 is started by tripping switch 62. This causes rotation of spindles 14 and the grinding stones 16 mounted thereon by means of the belts 64 and 68, pulleys 70 and 72 and the belts 74 and 76. A ceramic tile setter 3 is then placed on table 2 and forced onto the forks 6 which lift the tile setter 3 slightly free of table 2 and lines up or synchronizes the shelves 4 with the grinding stones 16 mounted on spindles 14. Clamp units 8 are then adjusted to hold the tile setter 3 in its elevated position. Lever 10 is then depressed moving the indexing box 12 to its lowest position against the lower indexing box stops 44b. At the same time the cam roller 90 mounted on said lever 10 will pass over one-way latch 86a mounted on the cam plate 22 and trips the limit switch 84a. The cam roller 90 then becomes positioned on the lower cam surface machined on said cam plate 22. Limit switch 84a after being tripped by the said cam roller 90 activates air cylinder 26. Since air cylinder 26 is operatively connected to table 2, it is adapted to move said table 2 in a longitudinal direction along guideways 28. The tile setter 3 positioned on table 2 is thus adapted to have one half of its shelves 4 ground in a desired manner as table 2 moves rearward past grinding stones 16. It should be noted that the said grinding stones 16 are spaced on the spindles 14 in a manner to grind every other shelf 4.

As table 2 moves rearward, the front of the lower cam surface On cam plate 22 being similar to the back cam surface except that latch 86b is reversed, curves upwards causing the cam roller 90 riding on the lower cam surface under a considerable pressure and lever 10 upon which the cam roller 90 is mounted to be forced upwards. Cam roller 90 then trips limit switch 84b and moves over one- Way lat-ch 86b, finally becoming positioned on the upper cam surface of cam plate 22. Since the indexing box 12 is attached to lever 10', it is also moved to its upper position against the upper indexing box stops 44a. The limit switch 841; tripped during the upward movement of said cam roller 90 reverses the action of air cylinder 26 and since table 2 is operatively connected thereto, it is forced in a direction opposite to that of its original movement along guideways 28. The spindles and attached grinding stones, now positioned in their second or upper position due to the upward movement of indexing box 12 on which they are mounted, are adapted to grind the remaining half of tile setter shelves 4 as table 2 passes to the front of the apparatus. As table 2 moves forward, cam roller 90 ridt @191 the top cam surface of cam plate 22 and is in a position at the end of the reversed air cylinder 26 movement such that a downward movement of the lever 10 by an operator will again initiate the identical action just described.

The tile setter grinding apparatus set forth above is adapted to machine or hone shelves 4 to produce the tile support surfaces 9 which support the tile 11 during the firing operations. These surfaces coincide with the plane p-p'. See FIGURES 3 and 4. It is to be noted that any point on the supporting honed surfaces 9 will not vary more than 0.015 inch above or below plane P-P thereby providing a required degree of accuracy between opposed tile support means.

Although applicants preferred embodiment is characterized by the article to be ground being positioned on applicants horizontally moving table, with applicants grinding media positioned on his vertically movable indexing member, it will be quite obvious that it is really a matter of choice as to whether the function of the horizontally moving table and vertically moving indexing member are interchanged.

That is, applicant could just as readily place his grinding media on his horizontally movable table, clamp his article to be ground on his vertically movable indexing member and achieve substantially the same result with but minor mechanical modification as required; the essence of my invention lying in my cam means which automatically programs and guides the relative reciprocal movements of the horizontally reciprocating table and the vertically reciprocating indexing member through their operating cycle.

Referring to FIG. 6, it will be seen that, using conventional means for fixing the motor and housing 52 to movable table 2, and clamping the item to be ground to indexing member 12, the ease with which the interchange can be accomplished, while still providing the same end result, will be readily apparent.

Obviously, there are many other variations and changes that can be made in the above invention without departing from the scope thereof. It is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. Apparatus for grinding a multiplicity of surfaces comprising a movable table reciprocal in a first plane with a cyclical, peripherally endless cam afiixed thereto and reciprocal therewith, single means for reciprocating said table and its cam in said first plane, said table carrying clamping means for firmly holding thereto an object to be ground, a reciprocally movable indexing member reciprocal in a second plane generally normal to said first plane, resilient means associated with said indexing member continually urging same toward a first reciprocal extremity thereof in said second plane, said indexing member carrying a rotatable grinding member and means to rotate same; lever means, operably linked with said indexing member and communicating with said cam via a cam follower for moving said indexing member against'the resistance of said resilient means, to its second reciprocal extremity in said second plane guided by said cam, said cam follower reciprocal with said indexing member, said single first mentioned means for reciprocating said table responsive to said indexing member at its second extremity to reposition said table and its clamping means to their opposite reciprocal extremity in said first plane, said resilient means responsive via said cam and lever means to the arrival of said supporting table and its clamping means at their last mentioned position, to reposition said indexing member to its first extremity, said single, first men tioned means for reciprocating said table in said first plane responsive to the arrival of said indexing member to its first extremity in said second plane, to move said table and its clamping means back to their starting point in said first plane.

2. Apparatus for grinding a multiplicity of surfaces comprising a movable table reciprocal in a first plane with a cyclical, peripherally endless cam affixed thereto and reciprocal therewith, single means for reciprocating said table and its cam in said first plane, said table carrying a rotatable grinding member and means to rotate said grinding member; a reciprocally movable indexing member reciprocal in a second plane generally normally to said first plane, resilient means associated with said indexing member continually urging same toward a first reciprocal extremity thereof in said second plane, said indexing member carryng clamping means disposed therein for firmly holding thereto an object having surfaces to be ground, lever means, operably linked with said indexing member and communicating with said cam via a cam follower, for moving said indexing member against the resistance of said resilient means, to its second reciprocal extremity in said second plane guided by said cam, said cam follower reciprocal with said indexing member, said single first mentioned means for reciprocating said table responsive to said indexing member at its second extremity to reposition said grinding member and its supporting table to their opposite reciprocal extremity in said first plane, said resilient means responsive via said cam and lever means to the arrival of said grinding means and its supporting table at their last mentioned position, to reposition said indexing member to its first extremity, said single first mentioned means for reciprocating said table in said first plane responsive to the arrival of said indexing member to its first extremity in said second plane, to move said table and its grinding member back to their starting point in said first plane.

3. The apparatus of claim 1 wherein the reciprocation stroke of an object to be ground clamped to said table substantially intersects one reciprocation stroke of said grinding member.

4. The apparatus of claim 1 wherein the reciprocation stroke of an object to be ground clamped to said table substantially intersects one reciprocation stroke of said grinding member, said single means for reciprocating said table is a single, reciprocating hydraulic cylinder and said resilient means are springs.

5. The apparatus of claim 2 wherein the reciprocation stroke of an object to be ground clamped to said indexing member substantially intersects one reciprocation stroke of said grinding member.

6. The apparatus of claim 2 wherein the reciprocation stroke of an object to be ground clamped to said indexing member substantially intersects one reciprocation stroke of said grinding member, said single means for reciprocating said table is a single, reciprocating hydraulic cylinder and said resilient means are springs.

References Cited UNITED STATES PATENTS 504,006 8/1893 Vogel 5 l--92 2,396,775 3/ 1946 Young 5192 2,475,455 7/ 1949 Nicholas 5l100 X 2,675,652 4/ 1954 Chiappulini 51l00 2,774,195 12/ 1956 Chapman 5192 2,874,517 2/1959 Markle 5134 2,917,873 12/1959 Jewett 5l--92 HAROLD D. WHITEHEAD, Primary Examiner US. Cl. X.R. 

